The invention relates to a spray nozzle arrangement for high pressure cleaning apparatus with an outlet nozzle of circular cross-section.
In high pressure cleaning apparatuses the necessity exists regularly to produce jets of different cross-sectional shape, in order to satisfy the various demands. Thus for example, for strongly adhering contamination (cleaning chains in building machinery, removal of dung in pigsties and the like), a point jet with a high impact pressure and small area output is required. For the cleaning of sensitive surfaces (lacquered car body parts, tile-covered floors and so forth), however, a flat jet is required which, for example, has an opening angle of 60.degree., a low impact pressure and large area output.
For producing these different jet forms, nozzle systems have been known heretofore, wherein change-over can be effected from one nozzle to another by actuation of a slider member. The displaceable parts of such a slider member system are sealed against each other by means of O-ring seals. A disadvantage of this construction resides in that it is restricted to a low number of fixedly predetermined jet shapes, for example two or three jet shapes. A stepless control of the jet shape and thus optimum adjustment to the prevailing circumstances is impossible.
Rotary change-over nozzles are also known in which four different nozzle openings with different jet angles are accommodated in a nozzle disc and are rotated by means of a resiliently pressed seal until the desired nozzle opening is arranged over the water supply bore. In this construction, too, stepless adjustment to the cleaning tasks is impossible.
It has also been proposed to insert a knife-edge body into one side of a high pressure jet in a nozzle arrangement and to change the shape of the jet in this way (German patent application Pat. No. 27 36 314.0). However, by inserting a knife-edge into one side of a round jet, a flat jet having the desired distribution of liquid and a uniform impact pressure over the entire jet width, such as is necessary for fulfilling the cleaning tasks, cannot be produced. Moreover, a great disadvantage of the arrangement described in patent application Pat. No. 27 36 314.0 resides in the fact that, due to the immersion of the knife-edge body, the spray direction of the jet is deflected and thereby the exit angle is changed relatively to the manually guided spraying device. Thereby the torque is altered which acts upon the spraying device (in such apparatus the liquid issues at a pressure of for example 100 atmospheres).
Furthermore, the jet change necessitates a complicated adjustment of the operator to this jet angle.
The German Pat. No. 471 399 describes a compressed air thrower device, in which a jet of compressed air is formed to a broad rectangular jet shape which is variable, for the purpose of throwing or conveying mortar. In this construction, the variable opening in conjunction with the static pressure of the compressed air in front of the nozzle determines the issuing quantity of compressed air and the exit speed of the compressed air. It is impossible in this arrangement to produce a round jet and to convert the same steplessly to a flat jet, such as is necessary in high pressure cleaning apparatus.
Finally a device for changing the jet of a gardening hose is known in which a tongue is inserted into one side of the issuing water jet by means of a lever which must be actuated by hand, and thereby effects a fanformation of the jet (U.S. Pat. No. 3,003,706). With this kind of change the disadvantages of the irregular water distribution in the jet as well as the deflection of the jet from the original exit direction occur again--disadvantages which are certainly without importance for the intended purpose of use of watering the garden, but which are extremely important for the jet of a high pressure cleaning apparatus which jet issues at a high pressure. Moreover, the tongue must be continuously retained manually in the operative position by means of the lever and thereby ties down one hand. In high pressure cleaning, a hand in the vicinity of the issuing hot cleaning jet which is mixed with chemicals constitutes a risk. Moreover in high pressure cleaning, both hands are required for effecting the same, because of the loading occurring due to the high exit pressure.